对传统活性污泥法污水厂新增脱氮除磷的改造

Retrofit of a Traditional Activated Sludge Process to Achieve Nitrogen and Phosphorus Removal

某一传统活性污泥法污水处理厂没有脱氮除磷功能,处理规模为1.8×104m3/d。第一阶段已成功对原工艺的初沉池和曝气池第一廊道进行了改造,改造完后运行的第一阶段(第1~30天)出水COD、氨氮、TN浓度均达到《城镇污水处理厂污染物排放标准》(GB 18918—2002)的一级A标准,出水SS和TP平均浓度分别为12和0.8 mg/L,达到一级B标准。为了使出水SS、TP浓度也达到一级A标准,第二阶段在第一阶段的基础上在尾端模拟增加砂滤管并在管前端添加PAC,以进一步完成对工艺的改造研究。结果表明,第二阶段(第31~121天),出水SS为1~6 mg/L,平均为4 mg/L,平均去除率为97.5%;出水TP为0~0.46 mg/L,平均为0.22 mg/L,平均去除率为89.5%。出水COD、氨氮、TN、SS、TP均达到一级A标准。工艺改造成功实现了脱氮除磷目标,而且没有混合液回流(内回流),因此整个工程运行节能,为现有无脱氮除磷功能污水处理厂提标改造提供了思路。

A traditional activated sludge process plant, of a scale of 1.8 ×104 m3/d, has no nitro- gen and phosphorus removal function. In the first phase of the retrofit, the primary settling tank and the first corridor of the aeration tank of the system were redesigned, and the effluent COD, NH＋4 - N and TN all complied with the first grade A standard of Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant （GB 18918 -2002）, the average concentration of SS and TP in effluent were 12 mg/L and 0.8 mg/L, respectively, which complied with the first grade B standard. In the second phase, the process was further improved by adding a sand filter and PAC, in order to ensure the effluent SS and TP to reach the first grade A standard. Results showed that in the second stage, the effluent SS was 1 -6 mg/L, the average concentration of effluent SS was 4 mg/L,with an average removal rate of 97.5%. The effluent TP was 0 - 0.46 mg/L, the average concentration of effluent TP was 0.22 mg/L, and its average removal rate was 89.5%. The effluent COD, NH4＋ - N, TN, SS and TP all complied with the first grade A standard in the second stage. The process retrofit reached the goal of nitrogen and phosphorus removal without mixed liquid recycle, which was energy saving. The study set up an example for the municipal wastewater treatment plant retrofit which has no nitrogen and phosphorus removal.